The present invention relates to a dual-fuel injection system particularly for an internal combustion engine. In addition, the invention relates to a method of implementation using such a dual-fuel injection system. The invention can be used, in particular, with pilot ignition engines, which besides a pilot ignition mode with fuel gas (and a diesel or heavy oil pilot ignition) also provide a pure diesel or heavy oil mode. Here bio-oil or biofuel, for example, may also be used instead of heavy oil.
Gaseous fuels are becoming increasingly important in the (large) engine sector, especially in stationary engines for power generation. Natural gas is outstandingly suitable for an economic and environmental engine operation owing to its ready availability and its more favorable potential emissions compared to diesel fuel.
In those dual-fuel injection systems of generic type which use liquid fuel for (indirect) control of the gas injector unit(s) (principle: pilot valve-actuator-control chamber), especially systems which make use of high-pressure gas injection in conjunction with a pilot injection by diesel fuel or heavy oil (or biofuel), mixed leakage regularly occurs. The gas fraction of this mixed leakage is separated in separators, wherein the liquid fuel is fed back into the tank and the gas is recompressed or is fed into the engine intake tract. One disadvantage here is that the leakage is subjected to treatment without making any distinctions with regard to the operating situation, so that consequently the cost in terms of energy is not ideal.